If your Jumia app is not working, follow these step-by-step troubleshooting methods to resolve the issue:

1. Check Internet Connection: Ensure that your device has a stable internet connection. Switch between Wi-Fi and mobile data to see if that resolves the issue.

2. Restart the App: Close the Jumia app completely and then reopen it. This can refresh the app and might resolve minor glitches.

3. Clear App Cache and Data:
- Go to your device’s Settings.
- Navigate to Apps.
- Find and select the Jumia App.
- Tap on Storage and then select Clear Cache and Clear Data. This will reset the app, which can fix loading issues.

4. Update the App: Make sure you have the latest version of the Jumia app installed. Go to the Google Play Store or Apple App Store, search for the Jumia app, and update if necessary.

5. Reinstall the App:
- Uninstall the Jumia app from your device.
- Restart your device.
- Reinstall the app from the Google Play Store or Apple App Store.

6. Device Compatibility: Sometimes, app issues can arise due to device compatibility. Ensure your device meets the app's requirements.

7. Operating System Update: Check if your device's operating system is up-to-date. If not, update to the latest version as app functionality can depend on the latest OS updates.

8. Check for Server Issues: Sometimes, the problem may not be on your end. Check Jumia's social media pages or forums to see if there are ongoing server issues affecting users.

9. Consult Various Guides and Videos: There are many resources available that provide visual step-by-step instructions. You can refer to guides like "How to Fix Jumia App Is Not Working and Not Loading" on YouTube - learn more or "Fix JUMIA Online App Not Working / Loading / Not Open" - learn more.

If these steps do not resolve the problem, you may want to contact Jumia customer support for further assistance.